1. Field of the Invention
This invention relates generally to communications and more particularly to a method and system for real-time bit error ratio determination.
2. Description of the Related Art
In conventional communications networks, it has become increasingly important to be able to determine the accuracy with which data is transmitted. Attempts have been made to identify bit error occurrences in a number of networks, particularly those transporting critical and/or time sensitive data, in order to alert users and/or applications and avoid further error and damage. For example, in automation control networks used in the operation of manufacturing and process equipment. Failures in such networks (e.g., in motion control, process, or manufacturing operation processes) have safety and financial implications that are frequently more serious than failures in other data networks (e.g., file sharing, e-mail, or the like).
As Ethernet and other traditional networking layer 2 (L2) technologies have become prevalent in time-sensitive applications and communications networks, techniques to determine bit error occurrences in such environments have become more and more important. Traditionally, systems for identifying errors in such environments have implemented either “dedicated link” or “in place” monitoring systems. In “dedicated link” monitoring systems, physical test equipment is place at either end (e.g., transmit and receive) or a link within a communications network. A known sequence or bits is then transmitted across the link so that a definitive determination about any individual bit errors may be made. Unfortunately such “dedicated link” systems require specialized hardware for each link of a network and typically do not provide the capability to utilize the monitored link or network for ordinary data transmission while monitoring is being performed.
By contrast, “in place” monitoring systems or techniques use error detection techniques such as cyclic redundancy check (CRC) parity to determine the number of packet or frame errors occurring over a link. While “in place” monitoring systems allow links to be used for data transmission during monitoring, and do not require that the specific sequence of bits transmitted be known prior to transmission, they require that an entire packet or frame be transmitted and fail to provide information about individual bit errors.